There is most likely a problem with the pneumatic valve inside the Conflo interface. I would assume a blockage in the "dilution on" split section. If you remove the cover from the Conflo you will see a small pneumatic valve on the right. The Ea flow from the back of the interface connects to this valve. This valve switches from a split of the EA flow from 72ml/min with dilution off to 79.5ml/min with dilution on (flow rates based on 80ml/min EA flow; as in conflo manual pg 2-3). It does this by switching flow paths, one path being more restricted than the other.
It would appear that the "dilution on" flow path is clogged and creates a back pressure on the EA slowing flow. I would suggest disassembly of the valve and both flow paths and cleaning both thoroughly with acetone followed by MeOH. Dry parts well in a oven at ~30C. I would also suggest replacement (or at very least cleaning as above) of the glass capillary associated with the EA flow to the open split. While it is open, you may want to clean the open split glass as well, but it can be a pain to remove and reset all capillaries. Noticeable brown stains in the open split would suggest a need to perform this extra work.
Good Luck!

On Fri, Mar 28, 2008 at 12:10 AM, Melissa Bautista <[log in to unmask]> wrote:
Dear Isogeochemists,

This is in regards to a change in carrier flow rate from our Flash EA 1112
to a Conflo III.
The carrier flow is set at 100ml/min. However, when the He dilution
capillary is dropped in, the flow rate drops to c. 58ml/min. I have checked
the heights of the capillaries in the open split and they are positioned
correctly according to the manual. Can anyone tell me why this happens?

Thank you

Melissa Bautista
Southern Cross University
Lismore NSW Australia

"It isn't pollution that's harming the environment. It's the impurities in our air and water that are doing it."
US President, George W. Bush